This invention relates to protheses for implantation in an animal body and to the manufacture thereof. More particularly, the invention relates to macroscopically smooth, microporous, elastomeric tubular prosthetic devices and their manufacture from substantially non-elastomeric woven fabric tubes.
Vascular prosthetic devices are well known in the art and have been widely used in biomedical applications. The devices are used in reconstructive surgery, for example, where damaged blood vessels need to be replaced. Such prosthetic devices ideally should have the characteristic properties of natural blood vessels. Natural vessels are capable of returning to their original shape after being stretched, compressed, or bent and generally are not subject to kinking or radial collapse.
Vascular implants must be composed of biologically inert, biocompatible material. Materials that have been used in the past for prosthetic devices include Dacron (Dupont trademark for polyethylene terephthalate), Orlon (Dupont trademark for polyacrylonitrile), and Teflon (Dupont trademark for tetrafluoroethylene), though other materials may be appropriate.
Various prosthetic devices and methods of manufacture are known. Several patents, for example U.S. Pat. Nos. 2,836,181, and 3,142,067, disclose fabric tubes which are corrugated, crimped or folded to impart elasticity. In U.S. Pat. No. 3,337,673, a uniformly corrugated prosthetic device is disclosed. The device is formed by wrapping a tube with a filament at spaced intervals and pushing the ends of the tube toward each other. U.S. Pat. No. 3,096,560 discloses a prosthetic device with a smooth interior, but with a finely folded exterior structure. The problem, however, with these devices is that rough or sharp crimps and corrugations may irritate tissue surrounding the implant and thus hinder integration of the foreign implant into the animal body. The surface of natural blood vessels is smooth, and therefore a smooth implant free of crimps, corrugations and folds would be more like the natural vessel.
Accordingly, it is an object of this invention to provide a prosthetic device with improved characteristics for use as blood vessel replacement parts. Another object is to provide a macroscopically smooth, microporous, elastic prosthesis for implantation in animal bodies which need not be crimped, corrugated, or folded and to provide a process for making the prosthesis. Other objects are to provide a prosthesis which promotes integration of surrounding natural connective or other tissue, to provide a macroscopically smooth, microporous, elastic prosthesis with threads defining microscopic loops situated between circumferential threads, and to provide such a prosthesis which may be coated with a non-thrombogenic material resulting in a high degree of patency. Still other objects are to provide a prosthesis composed of biologically compatible and biologically inert material having a smooth, non-thrombogenic lumen resistant to shrinkage or collapse. Another object of the invention is to provide a prosthetic graft device with axially oriented fibers forming microscopic loops to increase the surface area per unit length of the graft and to provide elastic behavior, which device is porous but practically impermeable to blood and water. Yet another object is to provide a blood vessel replacement part which facilitate anastomosis and handling by the surgeon.
These and other objects of the invention will be apparent from the drawing, claims, and description which follow.